摘要:

AbstractNovel hot‐melt type flexible, tough, thermally stable, processable, thermoplastic, aromatic polyimides have been synthesized involving reaction of a keto‐ether containing diamine with hinged aromatic dianhydrides followed by thermal and chemical cyclodehydration. Inherent viscosity in DMAC at 35°C of the synthesized polymers ranged 1.02 to 1.4 dl/g (0.5% solution). The polymers showed a glass transition temperature (Tg) of 250°C to 180°C as determined by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Thermogravimetric analysis showed polymer stability up to 510°C, in both air and nitrogen atmospheres. All the polymers have shown good melt‐flow. Films of 1.5–2.8 ml thickness were made and tested for mechanical properties at room temperature, 177°C and 210°C. The developed films are suitable for adhesion of Ti/Ti specimens and showed a lap shear strength of 5575 psi. Melt‐fusion of the polymers gave tough moldings. Graphite cloth composites have been made and tested for mechan

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030101

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractVisible‐light‐sensitive positive type resists have been developed. The chemistry to form images is based on the cleavage of side chain ester bonds of poly(methacrylates) catalyzed by an acid which is generated on sensitized photodecomposition of a diphenyliodonium (DPI) salt. Homopolymers and copolymers of tert‐butyl methacrylate (BMA) and 2‐phenylpropyl‐2 methacrylate (PPMA) were used as acid labile polymers. Exposure of thin films of the poly(methacrylates) containing DPI salt and p‐dimethylaminobenzylidene derivatives to an Ar laser beam emitting 488 nm light and subsequent heat treatment resulted in solubility alteration of the polymers, which became soluble in a protic solvent system. Considerable reduction of film thickness was observed after heating an image‐wise exposed thin film of PPMA polymers. The minimum exposure energies of 488 nm light for the positive image formation were 60 mJ/cm2and 40 mJ/cm2for BMA and PPMA homopolymers,

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030102

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe carbonyl hemoglobin (CO‐Hb), which was used to prevent denaturation (metHb) during the preparation of samples, was encapsulated into lipid vesicles constituted from unsaturated phospholipid, cholesterol and unsaturated fatty acid. Unsaturated components were polymerized by γ‐irradiation to enhance the stability of bilayer membrane. An aqueous dispersion of resulting Hb vesicles was freeze‐dried in the presence of saccharides (50–200 mM) to obtain a dehydrated powder of Hb vesicles. Change in the vesicle size, the leakage of encapsulated Hb and the oxidation of Hb to metHb were not observed. Therefore, the long‐term storage of Hb vesicles can be realized as a

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030103

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the dependence of mechanical and thermal properties of heterogeneous blends of poly(carbonate) (PC) with poly(methyl‐methacrylate) (PMMA) and with poly(styrene) (PS) on the concentration of the components. PS displays a very weak phase coupling in blends with PC, whereas PMMA is characterized by a strong coupling to PC. Experimental results as well as predictions based on composite theories are reported.The general finding is that mechanical properties, such as the tensile modulus and the dynamic shear modulus, as well as thermal properties, such as thermal expansion, are (i) only weakly affected by the occurrence of a phase inversion and of a continuous phase morphology, (ii) vary continuously with the concentration of the components, and (iii) are rather insensitive to the strength of the phase coupling. The theoretical predictions on the concentration—property relationship for these properties, based on a self‐consistent approach, agree very well with those observed experimentally. The elongation at break as well as the yield stress, on the other hand, are strongly influenced by the nature of the phase coupling: a discontinuous variation of these properties with the composition is observed for PS/PC blends but not for PMMA/PC blends. The general conclusion is that a set of mechanical and thermal properties of heterogeneous blends can satisfactorily be predicted on the basis of rather simple composite the

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030104

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this paper, we present a rheological study of a compact layer of highly swollen gel beads. The flow regimes of these systems are modelled by an elastic sinusoid moving in a Newtonian fluid. This model predicts a yield stress varying with the square root of the elastic modulus of the gel bead. The slope at the origin (at zero velocity) of the flow curve is expected to depend only on geometrical parameters and on the solvent viscosity. The experimental data are in qualitative agreement with the theoretical predictions.

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030105

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractVarious diblocks, triblocks and a graft copolymer of butadiene with 4‐vinylpyridine short blocks have been prepared. They were complexed with ZnCl2to give ionomer‐like materials. For all copolymers, the Tgof the elastomeric block (−84°C to −91°C) was unchanged by complexation. For all diblocks and triblocks with short blocks (DPn∼ 3) the storage modulus was only slightly increased by comparison with uncomplexed materials. For the graft copolymer even with short blocks the material is less sensitive to temperature after complexation. For triblocks, when theDPnof the vinylpyridine blocks was high enough (15 units), complexes were associated in multiplets of large size and the elastomeric properties were retained

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030106

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030110

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

ISSN:1042-7147    

DOI:10.1002/pat.1992.220030111

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY